A still from Crude: The Real Price Of Oil, a film higlighting the plight of victims of an environmental catastrophe in Ecuador’s oil-producing Amazon region

A US federal court has ordered a documentary film-maker to hand over footage relating to pollution in the Amazon to the oil giant Chevron, the latest twist in a multibillion-dollar lawsuit.

Judge Lewis Kaplan, of the district court in Manhattan, yesterday ruled in favour of Chevron's request to view 600 hours of outtakes from the award-winning film Crude: The Real Price Of Oil.

The 105-minute film sympathises with the victims of an environmental catastrophe in Ecuador's oil-producing Amazon region, but Chevron hopes unused segments will help it to fend off potential damages of $27.3bn (£17.9bn).

Joseph Berlinger, who directed the documentary, said turning over footage would violate journalistic privilege and undermine the lawsuit in Ecuador, one of the biggest in history. Environmentalists fear Chevron will get ammunition and investigative film-makers fear their that integrity and ability to protect sources will be compromised.

But the judge ruled that transparency and justice would be served by allowing the company to view footage shot in Ecuador and the US over three years, including interviews with environmental activists such as Sting and his wife, Trudie Styler.

"Review of Berlinger's outtakes will contribute to the goal of seeing not only that justice is done, but that it appears to be done," the ruling said. "The court expresses no view as to whether the concerns of either side are supported by proof of improper political influence, corruption or other misconduct affecting the Ecuadorian proceedings."

Crude, released last year, focuses on the 17-year legal battle between Chevron and 30,000 Ecuadorians who say their land, rivers, wells, livestock and own bodies were poisoned by decades of reckless oil drilling in the rainforest.

The plaintiffs say Texaco – which was taken over by Chevron in 2001 – dumped 68bn litres of waste water between 1972 and 1990, causing an epidemic of diseases such as leukaemia. Some have called it the Amazon's Chernobyl.

Chevron says scientific tests show the water is safe, that the diseases have other causes, that Texaco cleaned up the site and pollution since then is the fault of the state company, Petroecuador.

An Ecuadorean judge based in Lago Agrio, a jungle town named after Texaco's headquarters, is expected to rule on the lawsuit within two months. Chevron, braced for defeat in what it says is a biased tribunal, has vowed to fight on.

Kent Robertson, a Chevron spokesman, welcomed the US ruling. "The raw footage from Crude is an objective account of what is truly occurring in the shadows of this lawsuit and we are eager to bring these events to light. Given the level of opposition to Chevron gaining access to the outtakes, we have to believe there is ... damning content that was left on the cutting room floor. It's in the interest of justice that these events are known more broadly."

He said Berlinger may have unwittingly captured misconduct by the Ecuadorean court and the plaintiffs' legal team. He cited a scene allegedly showing the legal team participating in a focus group with a supposedly neutral court expert – a segment included in the Sundance film festival screening but edited out of the DVD version.

The director said there was no smoking gun and the controversial scene was not of a focus group but a routine meeting that indicated no wrongdoing. Crude was a balanced film that gave Chevron's side of the story, Berlinger said.

Maura Wogan, Berlinger's lawyer, said the ruling would cause "grave harm" to documentary film-makers and investigative journalists, adding: "We're very surprised by the court's lack of sensitivity to journalists' privilege."

Berlinger said he had received support from hundreds of other filmmakers who feared a "chilling" impact on documentaries if sources' protection could not be guaranteed. The director said he would appeal against the ruling.